The present invention relates to a composition, method and product for coating human nails.
A variety of methods for beautifying and strengthening human nails are known. One such method involves the attachment of preformed artificial nails to human nails. Examples of such techniques are illustrated in the following U.S. Pat. Nos. 2,633,139 (Pettey); 2,688,331 (Bogoslowsky); 2,941,535 (Lappe); 2,979,061 (Greenman et al.); 3,487,831 (Jaume et al.); 3,502,088 (Jarby); 3,552,401 (Michaelson et al.); and 3,645,835 (Hodgson).
More particularly, the Lappe U.S. Pat. No. 2,941,535 describes a preformed artificial nail which is affixed to the surface of a natural nail by means of an adhesive. The adhesive may comprise a polymerizable acrylic ester monomer, such as ethylmethacrylate, methylmethacrylate, butylmethacrylate and the like, which preferably has a polymeric filler dissolved therein. According to this patent, the preformed artificial nail is provided with holes to permit the adhesive to form an interconnecting bond between an overcoat and an undercoat of the artificial nail, thereby more firmly affixing the artificial nail to the surface of the natural nail.
The Hodgson U.S. Pat. No. 3,645,835 describes a cast film consisting of a copolymer of 80% by volume ethoxyethylmethacrylate (EEMA) and 20% by volume hydroxyethylmethacrylate (HEMA) onto which is spread a solvent-based polyvinyl ethyl ether pressure-sensitive adhesive (note Example 6 at column 11, lines 35-50). The cast film may then be attached to a human nail by means of the pressure-sensitive adhesive.
Another technique for the treatment of nails is described in the Welanetz U.S. Pat. No. 3,425,426, whereby split or broken nails are repaired by means of a shear fabric patch. This technique is similar to the above-mentioned application of a preformed artificial nail to human nails in that both techniques involve the attachment of a solid, preformed lamina to the surface of a nail. On the other hand, these techniques are distinguishable from techniques involving the application of a curable or hardenable liquid substance to a nail, whereby this curable substance hardens on the surface of the nail in the absence of an attached, solid, preformed lamina. An example of the latter technique is provided in the Michaelson et al. U.S. Pat. No. 3,483,289. In this Michaelson et al. patent there is described a human nail coating comprising a plasticizer, an albuminoid, an organic solvent and one or more of a cellulosic derivative, a natural resin or a synthetic resin. When applied to a nail, this coating hardens primarily by solvent evaporation (See column 1, lines 61-65). Such hardened coatings permit broken or split nails to mend and to elongate by natural growth without further breaking or splitting.
The Shepherd et al. U.S. Pat. No. 3,574,822 describes the incorporation of cross-linkable hydrophilic hydroxy lower alkyl acrylates and methacrylates into cosmetic compositions. Shepherd et al. indicate that these compositions may be applied to the hair or skin, as well as to human nails.
In addition to mending and strengthening nails, a hardenable substance may be applied to the surface of nails to give the appearance of lengthened or elongated nails. According to such techniques, a hardenable substance may be supported over the end of a nail by means of a removable support. For example, the Feingenbaum U.S. Pat. No. 2,073,867 and the Sautter et al. U.S. Pat. No. 3,478,756 describe removable supports which are placed underneath the tips of the nail, whereas the Lappe U.S. Pat. No. 3,037,514 and the Lisczawaka U.S. Pat. No. 3,157,912 describe removeable molds which are placed over the upper surface of the nail. After the hardenable substance cures, the support is removed and the hardened coating may be filed to conform to the shape of an elongated nail.
Perhaps the most widely used products for mending and elongating natural nails are methacrylate resin based formulations, e.g., note the disclosures of U.S. Pat. Nos. 3,037,514 (Lappe); 3,157,912 (Lisczawka); and 3,478,756 (Sautter et al.). These formulations may consist of two parts that after mixing have a suitable consistency to make easy to shape coatings, hardening to form a nail-like material.
Chronologically, one of the first and probably still the most commonly known and marketed formulations comprise a liquid being principally a methylmethacrylate or lower alkyl methacrylate monomer and a powder being polymethylmethacrylate. The liquid part contains a polymerization accelerator and the powder a polymerization initiator. When mixed together, the accelerator and initiator trigger the free radical initiated polymerization of methacrylate resins causing the material to cure. In order to achieve a smooth, easy flowing and easy to shape mix, the powder should dissolve, at least in part, in the liquid prior to cure. Different additives are incorporated in the formulations contributing to improved esthetics, color stability, shelf-life and other characteristics of the material.
Unfortunately however, the formulations based on methylmethacrylate (or poly lower alkyl methacrylate)/polymethylmethacrylate resins have very serious inherent drawbacks and disadvantages. Methylmethacrylate is a known skin irritant and sensitizer. It possesses a strong and unpleasant odor and its vapors are toxic and irritating to the eyes. Ethyl, propyl, isopropyl and other lower alkyl methacryalates also have, although usually to a lower degree, the same negative characteristics as those of methyl methacrylate (being at the same time inferior as a solvent for polymethylmethacrylate and therefore, contributing to worse handling properties and poor esthetics of the material). Also methyl methacrylate based artificial fingernails have markedly better mechanical properties than those made of its homologues, especially with respect to flexural strength and brittleness. Another disadvantage of formulations based on methyl methacrylate and its homologues is a high exotherm during curing causing considerable discomfort to the person involved.
Several nail mender and lengthener formulations based on methacrylate resins other than lower alkyl methacrylates have been or are in use or described in the literature. For example, the Lee, Jr., et al. U.S. Pat. No. 4,058,442 and the Lee, Jr., et al. U.S. Pat. No. 4,104,333 describe formulations based primarily on tetrahydrofurfuryl methacrylate and aliphatic di- or polymethacrylates. These formulations, however, although apparently biologically less harmful than those based on lower alkylmethacrylates, also had serious drawbacks that were found very objectionable to users. In general, they were more difficult to apply than methyl methacrylate based formulations due to poor solubility of polymeric powder in the liquid part. After cure, the surface had a thick layer of partially cured material that made finishing difficult and time consuming. The cured material was brittle and once a crack formed, it propagated easily. The use of special plasticizing additives became a must in these formulations and while they were to some degree beneficial in improving flexibility and crack resistance of the cured material, their presence was undesirable from the point of view of ease of application and finishing and in some cases because of esthetics of the cured material.
Accordingly, there is a need in the art for compositions, methods and products for coating human nails.